High idle

[78_Monte970]

Hey guys, Ethan here. Recently i replaced the gas tank on my monte carlo, and now it is idling high and will not go down if i mess with the screw on the carb. Could this be due to the air in the fuel lines or does it sound more like a vacuum leak? Fast idle adjustment maybe? It was perfect before the tank swap. Any help appreciated, thanks.

 

[dedub]

Unlikely it's air, that usually gets flushed out within the first few seconds with a mechanical pump. Did you run or re-connect the fuel return line? Did you mess with the vapor (charcoal) canister? There are connections to your emissions from that can. Check for leaks with a can of starting fluid around the manifold and carb base.

 

[pontiacgp]

 

[78_Monte970]

Unlikely it's air, that usually gets flushed out within the first few seconds with a mechanical pump. Did you run or re-connect the fuel return line? Did you mess with the vapor (charcoal) canister? There are connections to your emissions from that can. Check for leaks with a can of starting fluid around the manifold and carb base.

Its deadhead style so no return line, only vent line. There is one hose missing from the charcoal canister so i capped it off, could that be it?

 

[dedub]

hmmm maybe. I recommend checking for leaks like I mentioned earlier with a can of starter fluid around all hose fittings, vacuum lines, carb base, ect. Kind of like using soapy water to check for leaks on a tire but this time it's vacuum.
Next, a nice tool to own is a vacuum gauge, they are inexpensive and are palm sized. if it reads anything less than around -16 psi, then you have vacuum issues. It also doubles up to tune your carburetor but that's beyond this thread.
I would check your choke also, it could be stuck.

 

[78_Monte970]

hmmm maybe. I recommend checking for leaks like I mentioned earlier with a can of starter fluid around all hose fittings, vacuum lines, carb base, ect. Kind of like using soapy water to check for leaks on a tire but this time it's vacuum.
Next, a nice tool to own is a vacuum gauge, they are inexpensive and are palm sized. if it reads anything less than around -16 psi, then you have vacuum issues. It also doubles up to tune your carburetor but that's beyond this thread.
I would check your choke also, it could be stuck.

My choke was stuck. Never bothered to take the air cleaner off. Thanks for the help anyway